Re: Decay-In-Storage

["Sandy Perle" <sandyfl@earthlink.net>]

> Just looking for the technical basis for the rule.

The only reference I can find can be found in the Rad Health 
Handbook, January 1970 edition, where it states the following on page 
205, Miscellaneous,

1. The activity of any radionuclide is reduced to less than 1% after 
7 half-lives (i.e., 2^-7 = 0.8%).

The references are:

1. Los Alamos Handbook of Radiation Monitoring, LA-1835 (3rd Ed.)
2. Health Physics Handbook - General Dynamics, OSP-379 (April 1963)
3. AERE, HP/L23

As stated previously, this is only a relative value, i.e., < 1%. The 
important factor is how much was initially there, and how much is 
currently there, after whatever decay time.

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Sandy Perle					Tel:(714) 545-0100 / (800) 548-5100   				    	
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